Document Detail

Two group I ribozymes with different functions in a nuclear rDNA intron.
MedLine Citation:
PMID:  7556099     Owner:  NLM     Status:  MEDLINE    
DiSSU1, a mobile intron in the nuclear rRNA gene of Didymium iridis, was previously reported to contain two independent catalytic RNA elements. We have found that both catalytic elements, renamed GIR1 and GIR2, are group I ribozymes, but with differing functionality. GIR2 carries out the several reactions associated with self-splicing. GIR1 carries out a hydrolysis reaction at an internal processing site (IPS-1). These conclusions are based on the catalytic properties of RNAs transcribed in vitro. Mutation of the P7 pairing segment of GIR2 abrogated self-splicing, while mutation of P7 in GIR1 abrogated hydrolysis at the IPS-1. Much of the P2 stem and all of the associated loop could be deleted without effect on self-splicing. These results are accounted for by a secondary structure model, in which a long P2 pairing segment brings the 5' splice site to the GIR2 catalytic core. GIR1 is the smallest natural group I ribozyme yet reported and is the first example of a group I ribozyme whose presumptive biological function is hydrolysis. We hypothesize that GIR1-mediated cleavage of the excised intron RNA functions in the generation and expression of the mRNA for the intron-encoded endonuclease I-DirI.
W A Decatur; C Einvik; S Johansen; V M Vogt
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  The EMBO journal     Volume:  14     ISSN:  0261-4189     ISO Abbreviation:  EMBO J.     Publication Date:  1995 Sep 
Date Detail:
Created Date:  1995-11-13     Completed Date:  1995-11-13     Revised Date:  2009-11-18    
Medline Journal Info:
Nlm Unique ID:  8208664     Medline TA:  EMBO J     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  4558-68     Citation Subset:  IM    
Section of Biochemistry, Molecular and Cellular Biology, Cornell University, Ithaca, NY 14853, USA.
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MeSH Terms
Base Sequence
Cell Compartmentation
Cell Nucleus / genetics
DNA Mutational Analysis
DNA, Ribosomal / genetics*
Models, Genetic
Molecular Sequence Data
Myxomycetes / genetics*
Nucleic Acid Conformation
Polymerase Chain Reaction
RNA Splicing
RNA, Catalytic / classification,  genetics*,  metabolism
RNA, Ribosomal / genetics*,  metabolism
Sequence Deletion
Grant Support
Reg. No./Substance:
0/DNA, Ribosomal; 0/RNA, Catalytic; 0/RNA, Ribosomal

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